Impact of Dispersion of gases from combustion of Coal tar
Dissertation Submitted
To
The department of Chemical Engineering
Of
National Institute of Technology, Rourkela
In partial fulfillment of the requirements
For the degree of
Bachelor in Technology
By
V Divya Sree
(Roll no. 111CH0425)
Under the supervision of
Dr. BASUDEB MUNSHI
Department of Chemical Engineering
National Institute of Technology Rourkela,
Rourkela- 769008, Odisha, India
Chemical Engineering
National Institute of Technology Rourkela
Rourkela-769008, Odisha, India.
Certificate
This is to certify that the work in the thesis entitled Impact of Dispersion of gases from
combustion of Coal Tar, by V Divya Sree bearing roll number 111Ch0425 is a record of
an original thesis work carried out by her under my supervision and guidance in partial
fulfillments of the requirements for the award of degree of Bachelor of Technology in
Chemical Engineering
Dr. Basudeb Munshi,
Assistant Professor,
NIT Rourkela.
Declaration
I hereby declare that all the work contained in this report is my own work unless
otherwise acknowledged. Also, all of my work has not been previously submitted for any
academic degree. All sources of quoted information have been acknowledged by means
of appropriate references
V Divya Sree
111CH0425
Department of Chemical Engineering
National Institute of Technology Rourkela,
Rourkela- 769008, Odisha, India
Acknowledgement
I would like to express my deepest gratitude to the people who helped me with the work
presented in this dissertation, be it through supplying alternative and usually simplifying
views during scientific discussions, or through moral support during periods of stress and
doubt, or by providing the possibility of embarking on the extraordinary experience of
participating in this adventure.
Firstly, I am deeply indebted to my supervisor, Dr. Basudeb Munshi. He provided an
open and free environment that allowed me to choose this topic and provided valuable
insight that helped me in completing the project. I would also like to acknowledge his
exemplary guidance, monitoring and constant encouragement throughout the course of
this thesis.
I present many thanks to all my professors who over the years have molded me in the
field of Chemical Engineering. I would like to convey my special regards to Mr. Akhilesh
Sir for helping me with the rapid software without whom this project would be almost
incomplete.
I am very much thankful to those, who have been giving inspiration and kind advice
without which, it would not have been possible for me to complete this project work .I
thank all my friends and well-wishers who have rendered help in this endeavor.
I
ABSTRACT
This project ‘Impact of Dispersion of gases from combustion of Coal tar’ deals with
gases released during combustion of Coal tar and the area affected by these gases. This
depends on many parameters. This is solved by using the software “ANSYS”. For
modeling, the parameters which affect the flow of gases are need to be known. In general,
wind flow, presence of obstacles and temperature may affect the flow.
II
CONTENTS
Abstract………………………………………………………..……….………...I
List of figures…………………………………………………………………...IV
1. Introduction………………………….……………………………….….........1
1.1 Coal tar ……………………………..………….………………….………….1
1.2 Chemical composition………………………….…………………….……....1
2. Literature Review………………………………………………….….………2
2.1 ANSYS SOFTWARE……………..…………………….…………….………2
2.2 Parameters effecting the flow…………………………………………...…....2
2.3 Summary of review……………………………………………………….…..3
3. Modeling and simulation …………………………………………………….4
3.1 Problem statement……………………………………………….……............4
3.2 Mesh……………………….. ……………………………………….......…....5
3.3 Modeling equations……………………………………………..……………6
3.4 Solution methodology………………………………………….……………..6
4. Effect of wind velocity on dispersion of gases…………………..………........7
4.1 Dispersion of gases at 1m/s.……………………………………………..........7
4.2 Dispersion of gases at 19m/s……...…………………………………………..9
5. Results & Discussion………………………………………………….............11
5.1 Wind velocity at 1m/s…………………………………………………………11
III
5.2 Wind velocity at 3m/s…………………………………………………………13
5.3 Wind velocity at 5m/s…………………………………………………………14
5.4 Wind velocity at 7m/s…………………………………………………………16
5.5 Wind velocity at 9m/s..…………………………………………………...........18
5.6 Wind velocity at 11m/s…………………………………………………………20
5.7 Wind velocity at 13m/s…………………………………………………………21
5.8 Wind velocity at 15m/s…………………………………………………………23
5.9 Wind velocity at 17m/s…………………………………………………………25
5.10 Wind velocity at 19m/s……………………………………………………......26
6 Conclusion…… ……………………………………………………………….......30
7 References………………………………………………………………………….31
IV
List of figures
Figure 3.1: Geometry…………………………………………………………………….4
Figure 3.2: Mesh………………………………………………………………………....5
Figure 4.1.1: Contour of SO2 at Wind velocity 1m/s…………..….……………………..7
Figure 4.1.2: Contour of NOx at wind velocity 1m/s…….……………………………...7
Figure 4.1.3: Contour of CO at wind velocity 1m/s……………………………………..8
Figure 4.1.4: Contour of CO2 at wind velocity 1m/s…………………………………….8
Figure 4.2.1: Contour of SO2 at Wind velocity 1m/s…………..….……………………..9
Figure 4.2.2: Contour of NOx at wind velocity 1m/s…….……………………………...9
Figure 4.2.3: Contour of CO at wind velocity 1m/s……………………………………..10
Figure 4.2.4: Contour of CO2 at wind velocity 1m/s…………………………………….10
Figure 5.1.1: Graph of SO2 at Wind velocity 1m/s……………..….…………………….11
Figure 5.1.2: Graph of NOx at wind velocity 1m/s…..….…………….………………...12
Figure 5.1.3: Graph of CO at wind velocity 1m/s………………………………………..12
Figure 5.1.4: Graph of CO2 at wind velocity 1m/s………………………………………13
Figure 5.2.1: Graph of SO2 at Wind velocity 3m/s……………..….……………………13
Figure 5.2.2: Graph ofCO2at wind velocity 3m/s………..……………………………...14
Figure 5.3.1: Graph of CO at wind velocity 5m/s……….………………………………14
Figure 5.3.2: Graph of CO2 at wind velocity 5m/s………………………………………15
Figure 5.3.3: Graph of NOx at Wind velocity 5m/s…………..….………..……………15
V
Figure 5.3.4: Graph of SO2 at wind velocity 5m/s.…..….…………….…………………16
Figure 5.4.1: Graph of SO2at wind velocity 7m/s……………………………………….16
Figure 5.4.2: Graph of NOx at wind velocity 7m/s.……………………………………..17
Figure 5.4.3: Graph of CO2 at Wind velocity 7m/s……………..….……………………17
Figure 5.4.4: Graph of CO at wind velocity 7m/s………..……………………..………..18
Figure 5.5.1: Graph of SO2 at wind velocity 9m/s……….………………………………18
Figure 5.5.2: Graph of NOx at wind velocity 9m/s………………………………………19
Figure 5.5.3: Graph of CO at Wind velocity 9m/s…………..….………..………………19
Figure 5.5.4: Graph of CO2 at wind velocity 9m/s.…..….….………….…….…………..20
Figure 5.6.1: Graph of SO2 at wind velocity 11m/………………………………………20
Figure 5.6.2: Graph of NOx at wind velocity 11m/s.……………………………………21
Figure 5.7.1: Graph of SO2 at Wind velocity 13m/s……..………..….………………….21
Figure 5.7.2: Graph of CO at wind velocity 13m/s………..……………………………..22
Figure 5.7.3: Graph of CO2 at wind velocity 13m/s………...……………...……………22
Figure 5.7.4: Graph of NOx at wind velocity 13m/s…………………….………………23
Figure 5.8.1: Graph of CO at Wind velocity 15m/s……..………..….…………………..23
Figure 5.8.2: Graph of CO2 at wind velocity 15m/s………..……………………………24
Figure 5.8.3: Graph of NOx at wind velocity 15m/s………...…………...……………...24
Figure 5.8.4: Graph of SO2 at wind velocity 15m/s…………………….……………….25
Figure 5.9.1: Graph of CO2 at Wind velocity 17m/s…………..….……………………..25
Figure 5.9.2: Graph of CO at wind velocity 17m/s……..……………………..…………26
VI
Figure 5.10.1: Graph of SO2 at Wind velocity 19m/s……..………..……………………26
Figure 5.10.2: Graph of NOx at wind velocity 19m/s………..……..…………………...27
Figure 5.10.3: Graph of CO at wind velocity 19m/s…..…...…………...………………27
Figure 5.10.4: Graph of CO2 at wind velocity 19m/s………………….………………...28
1
1. INTRODUCTION
1.1 Coal tar
Coal tar is a brown or black liquid of extremely high viscosity. It is among the
byproducts when coal is carbonized to make coke. This is mixture of Phenols, polycyclic
aromatic hydrocarbons and heterocyclic compounds. The composition of coal tar is
influenced by the origin and composition of coal and also by the nature of distilling
process. As a result, it is referred by many names coal tar, crude coal tar, coal tar pitch,
coal tar creosote.
Combustion of coal tar is burning coal tar in presence of oxygen .The gases released
are Sulphur dioxide, carbon monoxide, carbon dioxide, NOx. Some particulates are also
released like ash.
1.2 Chemical composition (%)
Carbon 92-93
Hydrogen 4.3-4.7
Sulphur 0.3-0.8
Nitrogen 1.7-1.8
Oxygen 0.8-1
Ash content 0.2-0.3
Density 1.2-1.3gm/cm3
2
2. LITERATURE REVIEW
This chapter summarizes all the back ground reading done to gain enough
knowledge of software Ansys, parameters affecting the flow of cloud.
2.1 ANSYS
Ansys is an Engineering simulation software. Out of the different programs present,
ANSYSCFD is mostly used. ANSYS CFD is used in systems by simulating fluid Flows
in a virtual environment. This is mostly used in aircraft hydrodynamics, hydro cyclones
etc.
The present project work utilizes ANSYS 15.0 where Workbench is used for the
geometry purpose while the further simulation is done using Fluent 6.2.16. The mass
fraction of different gases and pressure profiles are observed at different velocities of the
wind and at different velocities of the gases coming out. The mass fraction for different
gases at different distances along the horizontally and as well as vertically are obtained
and are checked with ambient conditions.
2.2 PARAMETERS AFFECTING THE FLOW
The gases released generally form a cloud and move. At low concentrations all
the gases are transported and dispersed through the atmosphere in the same way. The
internal cloud buoyancy is the measure of whether the in cloud density is greater than or
less than the ambient or environmental density. If the cloud density is greater than
ambient density, it is called dense. If it is less dense, then it is called buoyant, and it may
rise several hundred meters away
The turbulent dispersion(i.e. rate of speed in lateral ,vertical ,downward
direction)of the cloud about its center of mass depends on atmospheric turbulence in the
atmosphere which itself depends on surface roughness conditions, the wind speed, and
stability(i.e. day or night).because of this the geographic area covered by the cloud will
increase ,thus affecting larger population .Buoyant turbulence is generated by heating of
3
the ground surface by the sun and its suppressed by cooling of the ground surface at
night.
Urban heat-Because of heat generated by human activities, including industrial
processes, urban or industrial areas is often several degrees warmer than its surroundings.
This causes the cloud to be neutral or unstable.
Aerosols and particles with sizes greater than about 10micrometer will have
appreciable settling velocities. For e.g., cloud of 200 micrometer aerosols released near
the ground will settle to the ground in a few minutes. Particles less than 10 micrometer
have velocities so small that they remain suspended.
2.4 SUMMARY OF REVIEW
This chapter has gone over all the concepts vital to this project in detail. It has covered all
the background knowledge in the field of dispersion of gases that is necessary for the
simulation.
4
3. MODELLING AND SIMULATION
3.1 THE PROBLEM STATEMENT
The present project work consists of 3D rectangular area having horizontal distance
of1000m, vertical distance of 3500m and width of 500m. Inside the rectangular area coal
tar is combusted at a temperature of 500k, in an area of 5*5 m at a distance of 50 m from
the flow of wind. Wind is flowing in positive X-direction and considering the different
velocities of wind as 1m/s, 3m/s, 5m/s, 7m/s,9m/s,11m/s,13m/s,15m/s,17m/s,19m/s.
velocities of gases are taken as 1 m/s. Mass fractions of the pollutants (SO2, NO2, CO,
PPM10) coming out are known. Mass diffusivities of different pollutants with respect to
air are also known. For a constant value of gases velocity by varying the wind velocity,
different types of dispersion is observed. The geometry of the problem is created using
Workbench, followed by meshing. The rest of work which includes providing initial and
boundary conditions etc. is done in Fluent. Thus the concentration of pollutants at
different heights and horizontal distance is calculated using ANSYS. Tabulation and
plotting is done to get an idea about the relation among the pollutants concentration and
distance.
Figure 3.1 Geometry of the physical domain with length 1000m, breadth 500 and width
500m
5
Emissions of Pollutants (Mass fractions)
SO2- 0.003
NOx- 0.017
CO- 0.058
CO2- 0.92
3.2 MESH
Meshing is basic requirement for the simulation process. To analyse the fluid flow
problems, the flow domains are divided into the smaller subdomains. For the meshing,
fine tetrahedron mesh is done in 3d geometry. After that named selection was done which
was named as inlet, inlet1, symmetry, wall for the entire geometry.
Figure 3.2 Meshed Geometry of the physical domain
6
3.3 MODELLING EQUATIONS
3.3.1 Continuity equation
Equation for mass conservation equation or also known as continuity equation is written
as:-
3.3.1
3.3.2 Transport equation for species transport
For the species transport in ANSYS FLUENT it solves the transport equation inside the
domain which is given as :-
3.3.2
3.4 SOLUTION METHODOLOGY
For the simulation process Phase coupled SIMPLE was chosen for the pressure-velocity
coupling. Second order Upwind scheme was chosen for the discretization of partial
differential equation. In the final step of simulation iterations were given which were as
follows:-
Step size – 0.05
Number of steps – 10000
7
4. Effect of Wind Velocity on the Dispersion of Gases
4.1 Wind velocity of 1m/s
4.1.1 Dispersion of SO2
Figure 4.1.1 Dispersion ofSulphur dioxide
Contour clearly shows the dispersion of Sulphur dioxide gas .The dispersion is very less.
4.1.2 Dispersion ofNOx
Figure 4.1.2 Dispersion of Nitrogen oxide
Contour clearly shows the dispersion of nitrogen oxide gas .The downstream length
covered by the gas is less.
8
4.1.3 Dispersion of CO
Figure 4.1.3 Dispersion of Carbon monoxide
Contour clearly shows the dispersion of carbon monoxide gas.Dispersion is very less and
the mass fraction is maximum near the combusted area and it decreased in downstream
length.
4.1.4 Dispersion of CO2
Figure 4.1.4 Dispersion of Carbon dioxide
The extent of dispersion is less and the mass fraction is maximum near the area where
coal is combusted and it is reduced in the downstream length.
9
4.2 Wind velocity of 19m/s
4.2.1 Dispersion of SO2
The contour clearly shows the dispersion and it is very clear that the downstream length
to which the gas had been dispersed is more than that compared to the length covered by
gas at 1m/s.
Figure 4.2.1 Dispersion of Sulphur dioxide
4.2.2 Dispersion of NOx
Figure 4.2.2 Dispersion of Nitrogen oxide
The dispersion is high in this case as compared to that of wind velocity at 1m/s.
10
4.2.3 Dispersion of CO
Figure 4.2.3 Dispersion of Carbon monoxide
The contour clearly shows the dispersion and it is very clear that the downstream length
to which the gas had been dispersed is more than that compared to the length covered by
gas at 1m/s.
4.2.4 Dispersion of CO2
Figure 4.2.4 Dispersion of Carbon Dioxide
The dispersion is high in this case as compared to that of wind velocity at 1m/s.Mass
fraction is decreasing in the downstream.
11
5. RESULTS & DISCUSSION
Level 1 is taken as ground level .Level 2 is at a distance of 4m from ground level. Level 3
is taken at a distance of 8m from ground level. Level 4 is taken at a distance of 12m from
ground level. Level 5 is taken at a distance of 16m from ground level. Level 6 is taken at
a distance of 25m from ground level.
5.1 Wind velocity at 1m/s
Figure 5.1.1 Sulphur dioxide dispersion
SO2gas is following a particular trend when the inlet velocity is 1m/s at all the levels.
The downstream length affected by the gas is 130m and the maximum mass fraction is
present on ground at a distance of 100m.
0
0.00001
0.00002
0.00003
0.00004
0.00005
0.00006
0.00007
0.00008
0.00009
-10 10 30 50 70 90 110 130 150
mas
s fr
acti
on
Distance(m)
level 1
level 2
level 3
level 4
level 5
level 6
12
Figure 5.1.2 NOx dispersion
NOx gas is following a particular trend at all levels and the downstream length affected
by the gas is 130m and the maximum mass fraction is 0.00045 on ground is at a distance
of 100m.The concentration of the gas has been decreasing from level 1 to level 6 and
maximum concentration is at level 1.
Figure 5.1.3 Carbon monoxide dispersion
CO gas is following a particular trend at all levels and the downstream length affected by
the gas is 130m and the maximum mass fraction is 0.0016 on ground is at a distance of
95m.At 25m height the concentration of gas has become zero.
0.00E+00
1.00E-04
2.00E-04
3.00E-04
4.00E-04
5.00E-04
-10 10 30 50 70 90 110 130 150
mas
s fr
acti
on
Distance(m)
level 1
level 2
level 3
level 4
level 5
level 6
0.00E+00
2.00E-04
4.00E-04
6.00E-04
8.00E-04
1.00E-03
1.20E-03
1.40E-03
1.60E-03
1.80E-03
-10 10 30 50 70 90 110 130 150
mas
s fr
acti
on
Distance(m)
level 1
level 2
level 3
level 4
level 5
level 6
13
Figure 5.1.4 Carbon dioxide dispersion
CO2 gas is following a particular trend at all levels and the downstream length affected
by the gas is 140m and the maximum mass fraction is 0.025 on ground is at a distance of
97m.The concentration of the gas has been decreasing from level 1 to level 6 and
maximum concentration is at level 1.
5.2 Wind velocity at 3m/s
Figure 5.2.1 Sulphur dioxide dispersion
SO2 gas had moved 270m downstream distance and the maximum mass fraction is
0.000017 on ground and the concentration has been decreasing as the height has been
increasing.
0.00E+00
5.00E-03
1.00E-02
1.50E-02
2.00E-02
2.50E-02
3.00E-02
-10 10 30 50 70 90 110 130 150
mas
s fr
acti
on
Distance(m)
level 1
level 2
level 3
level 4
level 5
level 6
0
0.000005
0.00001
0.000015
0.00002
0 50 100 150 200 250 300mas
s fr
acti
on
lenth(m)
level 1
level 2
level 3
level 4
level 5
level 6
14
Figure 5.2.2 Carbon dioxide dispersion
CO2 gas had moved 260m downstream distance and the maximum mass fraction is
0.00032 on ground and the concentration has been decreasing as the height has been
increasing. The distance covered by the gas has increased as we increased the velocity.
5.3 Wind velocity at 5m/s
Figure 5.3.1 Carbon monoxide dispersion
CO gas had moved 350m downstream distance and the maximum mass fraction is 0.0003
on ground and the concentration has been decreasing as the height has been increasing
and also in the downstream distance.
0
0.00005
0.0001
0.00015
0.0002
0.00025
0.0003
0.00035
0 50 100 150 200 250 300
mas
s fr
acti
on
downstream legth(m)
levell 1
level 2
level 3
level 4
level 5
level 6
0
0.00005
0.0001
0.00015
0.0002
0.00025
0.0003
0.00035
0 50 100 150 200 250 300 350
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
15
Figure 5.3.2 Carbon dioxide dispersion
CO2 gas had moved 360m downstream distance and the maximum mass fraction is
0.0049 on ground and the concentration has been decreasing as the height has been
increasing. The distance covered by the gas has increased as we increased the velocity.
Figure 5.3.3 Nitrogen oxide dispersion
NOx gas had moved 370m downstream distance and the maximum mass fraction is
0.00009 on ground and the concentration has been decreasing as the height has been
increasing and the concentration at level 6 is minimum which is nearly 0.00001.
0.00E+005.00E-041.00E-031.50E-032.00E-032.50E-033.00E-033.50E-034.00E-034.50E-035.00E-03
-50 50 150 250 350
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
0
0.00001
0.00002
0.00003
0.00004
0.00005
0.00006
0.00007
0.00008
0.00009
0.0001
-30 20 70 120 170 220 270 320 370
mas
s fr
acti
on
length(m)
level 1
level 2
level 5
level 3
level 4
level 6
16
Figure 5.3.4 Sulphur dioxide dispersion
SO2 gas had moved 370m downstream distance and the maximum mass fraction is
0.000015 on ground and the concentration at level 6 is minimum which is nearly
0.000002.
5.4 Wind velocity at 7m/s
Figure 5.4.1 Sulphur dioxide dispersion
SO2 gas covered a distance of 550m and the maximum mass fraction is 0.000027 on the
ground and the concentration is decreasing downstream.
0
0.000002
0.000004
0.000006
0.000008
0.00001
0.000012
0.000014
0.000016
0.000018
0 50 100 150 200 250 300 350
mas
s fr
acti
on
length(m)
level 1
level 2
leevl 3
level 4
level 5
level 6
0
0.000005
0.00001
0.000015
0.00002
0.000025
0.00003
0 100 200 300 400 500 600
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
17
Figure 5.4.2 Nitrogen oxide dispersion
NOx gas had moved 550m downstream distance and the maximum mass fraction is
0.00015 on ground and the distance covered by the gas is more compared to the
dispersion at wind velocity less than 7m/s.
Figure 5.4.3 Carbon dioxide dispersion
CO2gas had moved 550m downstream distance and the maximum mass fraction is 0.009
on ground at a distance of 100m and the concentration had been decreasing as it is
moving downstream.
0
0.00005
0.0001
0.00015
0.0002
0 100 200 300 400 500 600
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
0.00E+00
1.00E-03
2.00E-03
3.00E-03
4.00E-03
5.00E-03
6.00E-03
7.00E-03
8.00E-03
9.00E-03
1.00E-02
0 100 200 300 400 500 600
mas
s fr
cati
on
downstream length(m)
level 1
level 2
level 3
level 4
level 5
level 6
18
Figure 5.4.4 Carbon monoxide dispersion
CO gas had moved 550m downstream distance and the maximum mass fraction is
0.00055 on ground and the distance covered by the gas is more compared to the
dispersion at wind velocity less than 7m/s. and the trend followed by the gas in all levels
is almost the same.
5.5 Wind velocity at 9m/s
Figure 5.5.1 Sulphur dioxide dispersion
SO2 gas is following a particular trend at all levels and the downstream length affected by
the gas is almost 700m and the maximum mass fraction is 0.000045 on ground is at a
distance of 100m.At 25m height the concentration of gas is not so less compared to
ground level.
-1E-04
1.2E-18
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
0 100 200 300 400 500 600
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
0
0.000005
0.00001
0.000015
0.00002
0.000025
0.00003
0.000035
0.00004
0.000045
0.00005
0 100 200 300 400 500 600 700 800
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
19
Figure 5.5.2 Nitrogen oxide dispersion
NOx gas is following a particular trend at all levels and the downstream length affected
by the gas is 630m and the maximum mass fraction is 0.00025 on ground is at a distance
of 95m.The concentration of the gas is decreasing as the height is increasing.
Figure 5.5.3 Carbon monoxide dispersion
CO gas is following a particular trend at all levels and the downstream length affected by
the gas is nearly 690m and the maximum mass fraction is 0.0009 on ground is at a
distance of 95m.
0
0.00005
0.0001
0.00015
0.0002
0.00025
0.0003
0 200 400 600 800
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5+Sheet2!$E$4
level 6
0
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
0.0007
0.0008
0.0009
0.001
0 100 200 300 400 500 600 700 800
mas
s fr
acti
on
length(m)
level 6
level 1
level 2
level 3
level 4
level 5
20
Figure 5.5.4 Carbon dioxide dispersion
CO gas is following a particular trend at all levels and the downstream length affected by
the gas is 6900m and the maximum mass fraction is 0.014 on ground is at a distance of
100m.The dispersion to higher levels is increasing compared to previous cases where
wind velocity is less than 9m/s.
5.6 Wind velocity at 11m/s
Figure 5.6.1 Sulphur dioxide dispersion
SO2 gas is following a particular trend at all levels and the downstream length affected by
gas is 7000m and the maximum mass fraction is 0.00002 on ground is at a distance of
98m.At 25m height also dispersion is quiet good with mass fraction 0.000005.
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0 100 200 300 400 500 600 700 800
mas
s fr
acti
on
length(m)
level 6
level 1
level 2
level 3
level 4
level 5
0
0.000005
0.00001
0.000015
0.00002
0.000025
0 100 200 300 400 500 600 700 800
mas
s fr
acti
on
e
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
21
Figure 5.6.2 Nitrogen oxide dispersion
Downstream length affected by the gas is 7000m and the maximum mass fraction is
0.00012 on grounds is at a distance of 98m.As the concentration of gas is very low and as
the velocity is more the gas at level 2 and level 3 had become zero at a distance of 300m.
5.7 Wind velocity at 13 m/s
Figure 5.7.1 Carbon monoxide dispersion
The downstream length affected by the gas is nearly 900m and the maximum mass
fraction is 0.00023 on ground.
0
0.00002
0.00004
0.00006
0.00008
0.0001
0.00012
0 100 200 300 400 500 600 700 800
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
0
0.00005
0.0001
0.00015
0.0002
0.00025
-100 100 300 500 700 900
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
22
Figure 5.7.2 Carbon dioxide dispersion
The downstream length affected by the gas is nearly 900m and the maximum mass
fraction is 0.0035 on ground and levels which have less concentration initially have
settled to ground at a distance of 300m.
Figure 5.7.3 Nitrogen oxide dispersion
The downstream length affected by the gas is nearly 900m and the maximum mass
fraction is 0.000065 on ground and the concentration has been decreasing as the height is
increasing.
0.00E+00
5.00E-04
1.00E-03
1.50E-03
2.00E-03
2.50E-03
3.00E-03
3.50E-03
4.00E-03
-100 100 300 500 700 900
mas
s fr
acti
on
length
level 1
level 2
level 3
level 4
level 5
level 6
0
0.00001
0.00002
0.00003
0.00004
0.00005
0.00006
0.00007
0.00008
-100 100 300 500 700 900
mas
s fr
acti
on
length(M)
level 1
level 2
level 3
level 4
level 5
level 6
23
Figure 5.7.4 Sulphur dioxide dispersion
The gas is following almost the same trend except at level 4 and the length covered by
gas is almost 900m.
5.8 Wind velocity at 15m/s
Figure 5.8.1 Sulphur dioxide dispersion
The downstream length affected by the gas is 900m and the maximum mass fraction is
0.0016 on ground. At 25m height the concentration of gas is nearly 0.000002.
0
0.000002
0.000004
0.000006
0.000008
0.00001
0.000012
0.000014
-100 100 300 500 700 900
mas
s fr
acti
on
length(m)
level 1
level 5
level 2
level 3
level 4
level 6
0
0.000002
0.000004
0.000006
0.000008
0.00001
0.000012
0.000014
0.000016
0.000018
0 50 100 150 200 250 300 350 400
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
24
Figure 5.8.2 Carbon dioxide dispersion
The downstream length affected by the gas is greater than 900m, and the maximum mass
fraction is 0.0003.The concentration of the gas is decreasing as the height increases.
Figure 5.8.3 Carbon dioxide dispersion
The downstream length affected by the gas is greater than 900m and the maximum mass
fraction is 0.0005 on ground .At 25m height the concentration of gas has become zero at
a distance nearly 400m.
0
0.00005
0.0001
0.00015
0.0002
0.00025
0.0003
0.00035
0 200 400 600 800 1000
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
0.00E+00
1.00E-03
2.00E-03
3.00E-03
4.00E-03
5.00E-03
6.00E-03
0 200 400 600 800 1000
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
25
Figure 5.8.4 Nitrogen oxide dispersion
The gas affects downstream length greater than 900m and the concentration is decreasing
down the downstream length.
5.9 Wind velocity at 17m/s
Figure 5.9.1 Carbon monoxide dispersion
The downstream length covered by the gas is 1000m, as the initial concentration is less
the concentration at the last level is less and it is settling on ground at a distance of 400m.
0
0.00001
0.00002
0.00003
0.00004
0.00005
0.00006
0.00007
0.00008
0.00009
0.0001
0 200 400 600 800 1000
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
0
0.00005
0.0001
0.00015
0.0002
0.00025
0.0003
0 200 400 600 800 1000
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
26
Figure 5.9.2 Sulphur dioxide dispersion
The downstream length covered by the gas is 1000m and as the height is increasing the
concentration has been decreasing.
5.10 Wind velocity at 19m/s
Figure 5.10.1 Sulphur dioxide dispersion
The gas is moving a downstream length greater than 1000m and at this velocity it is not
getting settled on ground and the maximum concentration is on ground and the value is
nearly 0.000011.
0
0.000002
0.000004
0.000006
0.000008
0.00001
0.000012
0.000014
0 200 400 600 800 1000
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
0
0.000002
0.000004
0.000006
0.000008
0.00001
0.000012
0 200 400 600 800 1000
mas
s fr
acti
on
length
level 1
level 2
level 3
level 4
level 5
level 6
27
Figure 5.10.2 Nitrogen oxide dispersion
The gas is moving a downstream length greater than 1000m and at this velocity it is not
getting settled on ground and the maximum concentration is on ground and the value is
nearly 0.00006.
Figure 5.10.3 Carbon monoxide dispersion
The gas is moving a downstream length greater than 1000m and at this velocity gas is
dispersed throughout instead of settling on ground.
0
0.00001
0.00002
0.00003
0.00004
0.00005
0.00006
0.00007
0 200 400 600 800 1000
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
-5E-05
6E-19
5E-05
0.0001
0.00015
0.0002
0.00025
0 200 400 600 800 1000
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
28
Figure 5.10.4 Carbon dioxide dispersion
The gas is moving a downstream length greater than 1000m and as Carbon dioxide
concentration is more, gas present at different levels is going beyond 1000m which is not
the case for NOx ,CO.
0.00E+00
5.00E-04
1.00E-03
1.50E-03
2.00E-03
2.50E-03
3.00E-03
3.50E-03
4.00E-03
0 200 400 600 800 1000
mas
s fr
acti
on
length(m)
level 1
level 2
level 3
level 4
level 5
level 6
29
At 1m/s wind velocity, gases had settled on ground at a distance of 150 m. At all levels,
gases followed a particular trend. As the wind velocity is increased to 3m/s, 5m/s, gases
had settled at a distance of 250 m, 350 m following similar trend at different levels. Level
6 which is at the maximum height compared to others has a very low concentration of
gases compared to all other levels. At wind velocity 6m/s, 7m/s gases had settled at a
distance of 550m, 650m.As the height from the ground level is increasing, the
concentration of gases is decreasing. At wind velocity 9m/s, 11m/s gases are covering
downstream distance of nearly 800m. As the wind velocity is increased above 13m/s,
gases crossed a downstream distance of 900m.Gases which are near to ground is settling
vastly compare to gases which are at a height more than 10m .At the max wind velocity
of 19m/s gases had crossed 1000m.As carbon dioxide concentration is more than Sulphur
dioxide, nitrogen oxide, carbon monoxide, this gas at 1000m/s wind velocity had crossed
1000m downstream length at different levels whereas for other gases they have been
dispersed and didn’t settle .As the wind velocity is increased gas concentration near to the
ground has been decreasing and as the height is increasing the concentration has been
increasing. As the wind velocity is increased from 1m/s to 9m/s particular gas at different
levels have been following the same trend whereas as the wind velocity is increased from
13m/s to 19m/s there is no such particular trend and the gas at different levels started
settling randomly. The maximum mass fraction for all the gases at wind velocities less
than 9m/s is at the ground level and at a distance of 90-100m roughly. As the Wind
velocity has been increasing the concentration of the gases at the level 6 has been
increasing.
30
CONCLUSION:
As the velocity is increased from 1m/s to 19m/s it is clear that the gases released from
combustion of coal tar are covering more distance in down wind direction. The maximum
concentrations of gases on ground level are mostly observed at a distance less than 100m.
The concentration of the gases at a particular wind velocity has been decreasing as the
height increases. As the velocity is increased from 1m/s to 9 m/s, concentration profiles
are following a particular path whereas, as the velocity is increased beyond 11 m/s,
ground level gases and gases at level 1 concentration are becoming zero as they are
travelling half the downstream distance travelled by other gases at the same velocity. As
the velocity is increased the concentration of gas settling on ground has decreased.
31
6. REFERENCES
[1]. http://en.wikipedia.org/wiki/Coal_tar
[2]. http://en.wikipedia.org/wiki/Atmospheric_dispersion_modeling
[3].Stevan R Henna and Rex E Britter (2002), ‘Wind flow and dispersion at industrial and
urban sites’ page 78
[4].Brunekreef B. and Holgate, S.T. (2002), ‘Air pollution and health’, page 213
[5].Guidelines for Chemical Process Quantitative Risk Analysis, By Center for
Chemical Process Safety (CCPS), page 65
[6]. Dennis P. Nolan, ‘Handbook of Fire and Explosion Protection Engineering
Principles’, page 51
[7]. Turner D B (1994), ‘Workbook of Atmospheric Dispersion Estimates: An
Introduction to Dispersion Modeling’ (2nd Edition) CRC Press.
[8].Lutgens F K and Tarbuck E J (1995) ‘The Atmosphere: An Introduction to
Meteorology (6th Edition)’, page 97
[9]. http://www.csun.edu/~vchsc00b/468/EOH468WK4.pdf
[10]. Guidelines for Consequence Analysis of Chemical Releases
By Center for Chemical Process Safety (CCPS), page 77